Pipeline systems and methods of assembling them have been known for a long time. The prior art is replete with patents directed to the couplings used to assemble such systems and to such methods. The advantages of being able to join various segments of pipe with quick connect coupling devices is obvious when compared to pipelines which are joined by other means such as welding. Thus, the use of segmented mechanical couplings for joining the ends of pipes has attained wide commercial acceptance and the coupling industry has grown steadly over the past few years.
The couplings commonly used today comprise arcuate pairs of coupling segments having keys or other projections which embrace the adjacent ends of a pair of pipes and essentially align with a pre-formed slot, groove, or surface bead on the pipe ends. Typically, these coupling segments have a provision for including a sealing gasket within an internal chamber of the segments which interfaces with the pipe ends and prevents them from leaking. When the coupling segments are bolted together they extend in essentially a continuous ring about the circumference of the pipe ends to form a pipe coupling which attempts to immoblize the pipe ends and eliminate or reduce the width of gaps between the pipe ends. However, differences in the diameter of stock pipe of the same nominal diameter result in a less than optimal immobilization of the pipe ends, or other problems arise which cause the pipe ends to flex from the center axis of the pipe, relative to each other, resulting in leaks and sags in long runs of pipe and other problems. Further, attempts at immobilizing pipe to prevent flex has resulted in pipe couplings which tend to disallow fexibility in expansion and contraction of the pipe, resulting in leaking pipe systems.
It would also be beneficial if the pipes did not have to be pre-formed in an extraordinary way such as slotting, grooving, or beading, and most beneficial if the couplings could be utilized on the surfaces of smooth pipes without a great deal of pre-preparation of the pipe ends. The fact that one does not have to deal with slotting, grooving, threading, or beading pipe, or with threads on pipe fittings such as welded outlets, tees, elbows, crossovers and the like, means that the operation of installing pipelines tends to become inexpensive, both from a materials standpoint and from a manual labor standpoint. Further, if one does not have to deal with welding studs, and or welding the couplings in place, this too provides a cost and time savings.
It would thus be desirable to have an economical coupling, that would save time and money in its installation, while having a coupling that accomplishes immobilization of the ends of the pipes to prevent severe flex problems, while at the same time allowing expansion and contraction of the pipe. It should be understood that "flex" as used in this industry refers to the degree of bending or bending movement that can occur between the pipe members if the pipe line system is put under stress. It would be a further advantage if one did not have to deal with complex coupling arrangements, grooving or beading of pipe ends, threading of elbows and tees and the like and could just join the pipe and its various fittings together with a minimum of effort wherein the couplings, tees, elbows, and the like would not be movable in the circumferential direction about the pipe.
It would be a most decided advantage if the resulting pipeline had essentially unrestricted flow of any material that was being conveyed by the pipeline and the only restriction on flow was the actual inside diameter of the pipeline itself. All of these advantages and more can be obtained with the instant invention.
There is a long list of U.S. Patents dealing with couplings for pipe, wherein various arrangements of grooves and keys, beads and keys, and pegs and slots, are used to couple pipes together, such patents being: U.S. Pat. No. 1,293,871 to Murray, issued Feb. 11, 1919; U.S. Pat. No. 2,752,173 to Kroos; U.S. Pat. No. 3,328,053 to Mattimore et al, issued June 27, 1967; U.S. Pat. No. 3,680,894 to Young, issued Aug. 1, 1972; U.S. Pat. No. 3,695,638 to Blakeley, issued Oct. 3, 1972; U.S. Pat. No. 3,756,629 to Gibb, issued Sept. 4, 1973; U.S. Pat. No. 3,999,785 to Blakeley, issued Dec. 28, 1976, U.S. Pat. No. 4,163,571 to Nash, issued Aug. 7, 1979; U.S. Pat. No. 4,348,041 to Imai, et al, issued Sept. 7, 1982; U.S. Pat. No. 4,471,979 to Gibb, et al, issued Sept. 18, 1984; U.S. Pat. No. 4,522,434 to Webb, issued June 11, 1985; U.S. Pat. No. 4,561,678 to Kunsman, issued Dec. 31, 1985; U.S. Pat. No. 4,601,495 to Webb, issued Jul. 22, 1986; U.S. Pat. No. 4,611,839 to Rung et al, issued Sept. 16, 1986; U.S. Pat. No. Des. 287,532 to Jones et al, issued Dec. 30, 1986; U.S. Pat. No. 4,639,020 to Rung et al, issued Jan. 27, 1987; U.S. Pat. No. 4,643,461 to Thau, Jr. et al, issued Feb. 17, 1987; U.S. Pat. No. 4,702,499 to deRaymond et al, issued Oct. 27, 1987; U.S. Pat. No. 4,702,500 to Thau et al, issued Oct. 27, 1987, and Canada 701,311 to Pflederer et al, the two most pertinent references to the invention disclosed herein being Murray, U.S. Pat. No. 1,293,871 and U.S. Pat. No. 3,756,629 to Gibb.
Murray deals with a method and a coupling for connecting smooth surfaced pipe at the ends of the pipe members. The coupling consists of a tubular sleeve, which is mounted over both ends of the the adjacent pipe ends. The sleeve has perforations or openings through the sleeve circumferentially around the sleeve. A metal rod is then inserted in each opening and an electrical current sufficient for welding is passed through the metal rod to weld the sleeve to the pipe, while depositing a welded projection on the pipe and through the opening with the comcomittant result that the sleeve is essentially welded to the pipe.
Gibb deals with a stud system of joining pipe using couplings that have been designed as an indented bridge to overlay the studs. Studs are first welded in a circumferential configuration on the outer surface of the edge of the pipe members and the indented bridge coupling is laid over the welded studs. In those cases when the bolts, or fastening means for the couplings are drawn together, the bridge draws down on the studs whereby the studs, residing in the indentions of the bridge, hold the pipe ends together. Gibb also discloses the use of a bridge in FIG. 14, which utilizes slots through which the welded studs are projected, said studs being threaded on their upper ends to receive threaded nuts in order to secure the bridge in place.